• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.273-282
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• 1992

The purpose of this study was to propose the utility which was evaluated the digital image processing and clinical application of the videodensitomery. The experiments were performed with IBM-PC/16bit-AT compatible, video camera(CCdtr55, Sony Co., Japan), an color monitor(MultiSync 3D, NEC, Japan) providing the resolution of 512×480 and 64 levels of gray. Sylvia Image Capture Board for the ADC(analog to digital converter) was used, composed of digitized image from digital signal and the radiographic density was measured by 256 level of gray. The periapical radiograph(Ektaspeed EP-21, Kodak Co., U. S. A) which was radiographed dried human mandible by exposure condition of 70 kVp and 48 impulses, was used for primary X-ray detector. And them evaluated for digitzed image by low and high pass filtering, correlations between aluminum equivalent values and the thickness of aluminum step wedge, aluminum equivalent values of sound enamel, dentin, and alveolar bone, the range of diffuse density for gray level ranging from 0 to 255. The obtained results were as follows: 1. The edge between aluminum steps of digitized image were somewhat blurred by low pass filtering, but edge enhancement could be resulted by high pass filtering. Expecially, edge enhancement between distal root of lower left 2nd molar and alveolar lamina dura was observed. 2. The correlation between aluminum equivalent values and the thickness of aluminum step wedge was intimated, yielding the coefficient of correlation r=0.9997(p<0.00l), the regression line was described by Y=0.9699X+0.456, and coefficient of variation amounting to 1.5%. 3. The aluminum equivalent values of sound enamel, dentin, and alvolar bone were 15.41㎜, 12.48㎜, 10.35㎜, respectively. 4. The range of diffuse density for gray level ranging from 0 to 255 was wider enough than that of photodenstiometer to be within the range of 1-4.9.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.85-93
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• 1986

The purpose of this study was to investigate the curing effect of visible light through tooth substance, 0.5mm, 1.0mm thickness of enamel and dentin were prepared. Experimental specimen were made by Bisfil M & Silux packing into cylindrical brass mold 6.0mm in diameter, 2.0mm and 3.0mm, in height. All specimen were irradiated by visible light (Grip type) model No. SDL-50 Shofu Co.) for 30 seconds through tooth substance. Experimental groups were classified into enamel group (group 1) and dentin group (group 2) according to the thickness of tooth materials and then were divided into 2 subgroups (0.5mm group and 1.0mm group). In experimental groups, visible light irradiated to the specimen through either 0.5mm in thick or 1.0mm in think of tooth material. In Control group specimen were prepared by direct irradiation on the specimen surface of visible light without through tooth substance. The hardness was measured with a Barcol hardness tester (Barber-Colman Co. U.S.A.) for each prepared specimen. The results were as follows: 1. In control group, there were higher hardness values than those of in experimental group. 2. In experimental groups, 0.5mm groups had higher hardness values than 1.0mm groups did. 3. The hardness value at top surface of the specimen were higher than the hardness of bottom surface in each group. 4. Bisfil M had higher hardness values than Silux. 5. In all specimen of 3.0mm height polymerization effect was not occurred at bottom surface except Bisfil M in control group.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.1-4
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• 1989

To determine the thickness of coronal hard structure the minimal distance between pupal surface and outer surface of crown was measured by means of Bowley gauge on extracted first molars. Upper(28 teeth) and lower(24 teeth) were carefully collected from 30-39 years of age and male. The teeth were split mesio-distally through central pit. On the split surface various part which are deeply related in cavity preparation were measured (schematic drawing). The results were as follows: A : Distance from mesio-cervical enamel to pulp chamber surface. upper $2.63{\pm}0.19$(mm) Lower $2.18{\pm}0.27$(um) B : Distance from mesial chamber ceiling to mesial surface upper $2.75{\pm}0.34$ Lower $2.62{\pm}0.31$ C : Distance from mesial chamber ceiling to occlusal surface upper $3.82{\pm}0.51$ Lower $3.49{\pm}0.50$ D : Distance from distal chamber ceiling to occlusal surface upper $4.28{\pm}0.69$ Lower $3.90{\pm}0.52$ E : Distance from distal chamber ceiling to distal surface upper $2.79{\pm}0.45$ Lower $2.41{\pm}0.40$ F : Distance from disto cervical enamel to pulp chamber surface upper $2.49{\pm}0.24$ Lower $2.39{\pm}0.25$.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.169-179
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• 2007

This study was to compare the microshear bond strength $({\mu}SBS)$ of light- and chemically cured composites to enamel coupled with four 2-step self-etch adhesives and also to evaluate the incompatibility between 2-step self-etch adhesives and chemically cured composite resin. Crown segments of extracted human molars were cut mesiodistally, and a 1 mm thickness of specimen was made. They were assigned to four groups by adhesives used: SE group (Clearfil SE Bond) AdheSE group (AdheSE), Tyrian group (Tyrian SPE/One-Step Plus), and Contax group (Contax) Each adhesive was applied to a cut enamel surface as per the manufacturer's instruction. Light-cured (Filtek Z250) or chemically cured composite (Luxacore Smartmix Dual) was bonded to the enamel of each specimen using a Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n=20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at 95% level. Also the interface of enamel and composite was evaluated under FE-SEM. The results of this study were as follows ; 1. The ${\mu}SBS$ of the SE Bond group to the enamel was significantly higher than that of the AdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin (p < 0.05). 2. There was not a significant difference among the hdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin. 3. The ${\mu}SBS$ of the light-cured composite resin was significantly higher than that of the chemically cured composite resin when same adhesive was applied to the enamel (p < 0.05). 4. The interface of enamel and all 2-step self-etch adhesives showed close adaptation, and so the incompatibility of the chemically cured composite resin did not show.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.1-8
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• 2007

This study compared the microshear bond strength (${\mu}SBS$) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level, The results of this study were as follows ; 1. The ${\mu}SBS$ of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel. 2. For Z 250, the ${\mu}SBS$ of AQ group ($9.95{\pm}2.51 MPa$) to enamel was significantly higher than that of Adper soup ($6.74{\pm}1.80 MPa$), but not significantly different with Xeno group ($7.73{\pm}2.01 MPa$). 3. For Luxacore, the ${\mu}SBS$ of Xeno group ($5.19{\pm}1.32\;MPa$) to enamel was significantly higher than that of Adper group ($3.41{\pm}1.19\;MPa$), but not significantly different with AQ group ($4.50{\pm}0.96\;MPa$).

• Restorative Dentistry and Endodontics
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• v.28 no.6
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• pp.491-497
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• 2003

The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using confocal laser scanning microscope and microtensile bond strength test of two adhesive systems. The dentin surface of human molars. sectioned to remove the enamel from the occlusal surface. Either Scotchbond Multi-Purpose(3M Dental Product, St. Paul, MN, U.S.A) or Clearfil SE Bond (Kuraray, Osaka, Japan) was bonded to the surface. and covered with resin-composite. The resin-bonded teeth were serially sliced perpendicular to the adhesive interface to measure the hybrid layer thickness by confocal laser scanning microscope. The specimen were trimmed to give a bonded cross-sectional surface area of $1\textrm{mm}^2$, then the micro-tensile bone test was performed at a cross head speed of 1.0 mm/min. All fractured surfaces were also observed by stereomicroscope. There was no significant differences in bond strengths the materials(p>0.05). However. the hybrid layers of three-step dentin adhesive system, SM, had significantly thicker than self-etching adhesive system. CS(p<0.05). Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths(p>0.05). Bond strengths of dentin adhesive systems were not dependent on the thickness of hybrid layer.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.457-464
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• 2005

The purpose of our study was to investigate whether the intrapulpal temperature during cavity preparation of enamel or dentin with Er:YAG laser still remained in range of safety for dental pulp protection when combined with appropriate water flow rate. The effect of different pulse repetition rates at the same pulse energy during ablation was evaluated as well. Caries-free, restoration-free extracted human molar teeth were prepared for the specimen and divided two experimental groups of enamel and dentin. Each group comprised 5 specimens and each of tooth specimens were embedded into a resin block each and measuring probe was placed on the irradiated pulpal walls. For experiments of dentin ablation, enamel layers were prepared to produce dentin specimen with a same dentin thickness of 2 mm. A pulse energy of Er:YAG laser was set to 300 mJ and three different pulse repetition rates of 20 Hz, 15 Hz and 10 Hz were employed. Laser beam was delivered with 3 seconds and less per application over enamel and dentin surfaces constant sized by $3\;mm{\times}2\;mm$ and water spray added during irradiation was a rate of 1.6 ml/min. Temperature change induced by Er:YAG laser irradiation was monitored and recorded While enamel was ablated, there was no significant difference of temperature related to pulse repetition rates(p=0.358) and temperature change at any pulse repetition rate was negligible. Significant statistical difference in temperature changes during cavity preparation in dentin existed among three different pulse groups(p=0.001). While temperature rise was noticeable when the dentinal wall was perforated, actual change of temperature due to Er:YAG laser irradiation was not enough to compromise safety of dental pulp when irradiation was conjugated with appropriate water spray. Conclusively, it can be said that cavity preparation on enamel or dentin with an Er:YAG laser is performed safely without pulp damage if appropriate volume of water is sprayed properly over the irradiated site.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.2
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• pp.278-286
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• 2008

Many studies regarding Casein phosphopeptides-amorphous calcium phosphate(CPP-ACP) have demonstrated the remineralization ability on the demineralized enamel surface. A question is still remained that how deep can the calcium (Ca) and phosphorus (P) ions supplied by the CPP-ACP paste penetrate into the enamel subsurface. The aims of this study were to measure the penetrating depth of Ca and P ions in the demineralized human enamel in vitro, and were to determine the amount and depth of Ca and P ions according to the duration. The amount and depth of Ca and P ions were measured by microscopic observation with Field Emission Scanning Electron Microscopy (FE-SEM; LEO SUPRA 55, Carl Zeiss, Germany) and Energy Dispersive X-ray Spectrometer (EDS; GENESIS 2000, EDAX, USA: Linescan of Calcium and Phosphorus). Freshly extracted four human 1st premolars were obtained from the Dept. of Pediatric Dent., Kyung Hee Univ. Buccal surfaces of the 1st premolars were covered with nail varnish to form a window on the middle third of buccal surface. All of the teeth with enamel windows were immersed in a solution of 0.1 M lactic acid, Carbopol C907 (carboxypolymethylene BF Goodrich, Cleveland, OH, USA) at pH 4.8, and then incubated for 7 days. Each tooth crown was sawn in half through the midline of buccal window along the long axis of premolar. The four blocks of premolars were immersed in a 10-times diluted solution of CPP-ACP paste (Tooth Mousse, GC Corp., Tokyo, Japan) for 1, 2, 3 and 5 weeks while the rests were immersed in a placebo solution (distilled water) for the same duration. Each specimen was embedded in epoxy resin, and was sectioned perpendicular to the window, using a water-cooled diamond blade saw. The spectrum density indices of Ca and P were measured in the sound, de- and remineralized enamels by FE-SEM and EDS. The Student's t test was performed to compare the Spectrum Density Indices (SDI) of sound, re-and demineralized enamels, and to compare the differences among the durations. Followings are the conclusion : 1. The penetration depth of the remineralizing ions (Ca & P) of CPP-ACP paste is related to the depth of demineralized enamel (approximately $1050{\sim}1350{\mu}m$). It is revealed that the penetration depth of both ions reaches full thickness of decalcification and even slightly into the sound enamel. 2. The Ca & P levels of remineralized enamels in 1, 2 weeks were significantly higher than those of the sound enamels (p<0.05). 3. No statistically significant difference of Ca & P levels was found in relation with the increasing duration of remineralization (p>0.05).

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.34-43
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• 2002

The purpose of this study was to compare microleakage and marginal hybrid layer in class V restorations using two one-bottle adhesives and one self-etching adhesive. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were pre-pared on buccal and lingual surfaces of 30 extracted human molar teeth. Prepared teeth were randomly divided into three treatment groups (n=30) and restored with three adhesives and composites: Single Bond/Filtek Z-250 (Group 1), Prime&BondNT/Esthet.X (Group 2), UniFil Bond/UniFil F (Group 3). For microleakage, samples were stored in room temperature water for 24 hours, thermocycled stained with 2% methylene blue dye, sectioned into halves, scored and analysed using Mann-whitney test and Wilcoxon signed rank sum test. For marginal hybrid layer, samples were sectioned into halves, treated with 10% phosphoric acid for 5 seconds, stored in 5% NaOCL solution for 24 hours, dried and gold coated. Occlusal and gingival margins of each sample were inspected under SEM. The results of this study were as follows ; 1. Microleakage at the occlusal margins was not evident in group 1 and group 2, but it showed in group 3 (p<0.05). 2. Microleakage in group 1 and group 3 was significantly lower than in group 2 at gingival margins (p<0.05). 3. Microleakage at gingival margins was greater than at occlusal margins in group 1 and group 2, but microleakage at occlusal margins was greater than at gingival margins in group 3 (p<0.05). 4. In group 1 and group 2, no gaps at occlusal margins showed. But gaps showed in group 3. Occlusal margins were free from a hybrid layer in all groups 5. The thickness of the marginal hybrid layers was 2.5~5 $\mu\textrm{m}$ thick in group 5 $\mu\textrm{m}$ thick in group 2 and 1.5 $\mu\textrm{m}$ thick in group 3. 6 There was no corelation between microleakage and thickness of marginal hybrid layer. In coclusion, the effect of dentin adhesives on microleakge in class V composite restorations was excellent when one-bottle adhesives were applied on enamel margin, and it was good when a self-etching adhesive was applied on dentinal margin. There was no corelation between microleakage and thickness of marginal hybrid layer.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.87-92
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• 2008

Purpose: In this study, we tried to compare marginal accuracy when produce ceramic crown using all ceramic materials and existent metal-ceramic system. Material and methods: All-ceramic systems were E-max (Ivoclar/Vivadent, Lichtenstein), Lava(3M, U.S.A.) and Wol-ceram(Teamziereis, Germany). Metal-ceramic system(PFG) was composed of Au-Pt alloy (Metalor, Switzerlandand) and overlying ceramic(D-sign, Ivoclar/Vivadent, Lichtenstein). We fabricated metal master die with upper diameter of 7.95mm, bottom diameter of 9.00mm, height of 5.00mm, and taper of $6^{\circ}$. All ceramic system used 0.5mm thickness ceramic coping, while metalceramic system used 0.3 thickness metal coping. By adding dentin and enamel ceramics on each coping, a crown with a proximal thickness of 1.0 mm and occlusal thickness of 2.0mm was fabricated. Pressure of 2kg was applied for 10 seconds on each crown with static load compressor. Before and after cementation, we measured the marginal gap at 4 points of each crown using optical microscope. The data was analyzed using a Student's t test and repeated-measures of analyses of variance(ANOVA) followed by a Bonferroni test. A p value<0.05 was considered significant. Results: As experiment results, marginal accuracy of wol-ceram and Lava is no good when compared with marginal accuracy of PFG. But marginal accuracy of E.max is good when compared with PFG. This result showed not significant. The marginal accuracy of E.max is good when compared with marginal accuracy of wol-ceram and Lava. Conclusion: The marginal accuracy of E.max is very good when compared with marginal accuracy of another group.